Triac lights automatically switch schematic

200W lamp switch control, power supply voltage is 220V, is about 100lx illumination light automatically turned on or off. In the ambient light is dark time sensitive resistor w

as high resistance, the voltage threshold switch input voltage of about 2 feet higher than 0.7 times, its output also showed a high resistance, so the grid voltage by dividing resistors followed by the positive half cycle transistor is turned on, and at the emitter electrode of each half cycle to form a trigger pulse, the load is energized. When strong light (more than 100lx), the threshold switch output terminal becomes negative, the transistor and the triac gate no current, the circuit fails. Circuit required by the DC voltage obtained after rectification diodes D1 and D2. Current control circuit requires about 15mA.